Current golf club shafts are made of metals or composite materials, and golf club heads are made of metals or metal alloys, such as stainless steel or titanium alloys. The golf club head is subject to large forces during impact with golf balls, which can decrease a golf club's period of usefulness if the components are not durable enough to withstand these forces.
Paint can protect golf club components from corrosion, but generally does not adhere well to titanium alloys. Even when a clear sealing coat is applied on top of the paint, the paint on a golf club head is not very durable and can be quickly chipped away by golf ball impacts.
Several U.S. patents disclose coated golf club components with the purpose of increasing component durability. For example, U.S. Pat. No. 5,458,334 to Sheldon, et al. discloses a golf club face “with a substantially harder material fused to it,” where “the resulting clubface is a homogenous, hard material.” The process disclosed in Sheldon involves a “micro-welding process” and “is not a coating process.” “Especially useful for the electrode [used in the micro-welding process] are the carbides of various metals such as tungsten carbide, titanium carbide, chromium carbide and other well-known metallic carbides.” Sheldon does not disclose a coated golf club component, but rather, a single homogenous fused layer of golf club component substrate and electrode material.
U.S. Pat. No. 6,723,279 to Withers, et al. discloses that a golf club component “may also be surface hardened . . . preferably by coating a titanium golf club structure with fullerenes and heat treating the coated structure to produce a titanium carbide surface.” “The important discovery is that the buckyballs provide an alloying bridge to the steel or titanium golf club surface and produces a carbide alloy surface that can be quite hard.” Similar to Sheldon, Withers discloses a surface layer of titanium carbide, directly fused to the golf club component substrate.
U.S. Pat. No. 6,196,936 to Meckel discloses a golf club component that “is coated with a corrosion-resistant, wear-resistant, impact-resistant material, such as zirconium nitride, titanium nitride, di-titanium nitride, titanium aluminum nitride, titanium carbonitride, titanium zirconium nitride, or titanium aluminum carbonitride.” In Meckel, “each layer is substantially homogenous and of uniform composition throughout,” and “in all cases, the total thickness of the coating 130, for the total of all the layers, is preferably from about 1½ to about 10 micrometers.” The coated golf club components disclosed in Meckel can be colorful, ranging from pink to “nearly black.”
Based on a machine translation, Japanese Patent Application No. 09-173114 (publication no. 11-004920) to Yoshinobu, et al. discloses a golf club head having a “flame-spraying layer of cemented carbide in the front face of the golf club head body formed with the metallic material which uses titanium as a principal component, and forming on it the coating layer which consists of a hard titanium compound.” In Yoshinobu, the preferred thickness of the titanium carbide coating layer “is several microns thru/or dozens of microns.” In Yoshinobu, a “beautiful” gray is obtained on the front face of the golf club head.
Also based on a machine translation, Japanese Patent Application No. 08-175818 (publication no. 10-000250) to Naoyuki, et al. discloses a golf club head having a surface preparation layer consisting of an “inner layer which uses titanium nitride (TiN) or titanium carbide (TiC) as a principal component” and an “outer layer which uses carbonization titanium nitride (TiCN) as a principal component.” The inner layer of titanium nitride or titanium carbide has a thickness of about “1.2 micrometers-4.5 micrometers.” Naoyuki praises homogenous coating layers because “[they excel] in the stability of a color tone. For example . . . gray becomes possible with titanium carbide (TiC).”
These and other coated golf club components have been developed, although none of these prior known golf club components is ideal. For example, conventional plating techniques do not provide wear resistance, and conventional physical vapor deposition techniques do not provide corrosion resistance for golf club components. Furthermore, golf club components having an aesthetically pleasing black color generally cannot be produced by conventional plating, conventional physical vapor deposition, nor the prior art methods disclosed above. Thus there is a need for an improved approach to protecting golf club components that can produce both an aesthetically pleasing appearance, such as a black color, and also function to prevent or substantially reduce corrosion and/or wear of the golf club component.